Paris - The roof of France's National Assembly is ready to buzz with activity after the arrival of three large bee hives this week as part of a project to promote pesticide-free honey.The bees are expected to be moved in once the weather warms up, should produce up to 150kg of honey a year and help pollinate flowering plants around the capital at a time of worldwide decline in bee numbers.The project is part of a new trend across Europe to put bee colonies on city rooftops, taking advantage of the fact that bees adapt well to urban living and can target the many varieties of long-blooming inner-city greenery."This is a great symbol for us," Thierry Duroselle, head of the Society of French Beekeepers, talking to Reuters about the new hives perched atop part of the grandiose 18th Century palace on the Seine River that houses the lower house of parliament."We think it's a nice opportunity to educate people - the public and politicians - on the role of bees."Despite their reputation for painful stings, bees are vital for human existence. A global decline in their numbers, the reasons for which are baffling scientists, is alarming everyone from farmers to European Union policy makers.The loss of habitat due to urban expansion, and, in France, an invasion of bee-eating Asian hornets, is adding to a phenomenon known as Colony Collapse Disorder.More than two-thirds of the 100 crop species that provide 90% of the world's food are pollinated by bees, including fruit, nuts and grains. A 2011 United Nations report estimates the work done by bees and other pollinators to help food crops reproduce is worth €153bn a year.The EU is still battling to agree on a ban of farm pesticides linked to the decline of honeybees, but studies show the insects adapt well to city living as the plants they encounter there have been treated with fewer chemicals.Fluffy black sheepWhile bee colonies adhere to a firmly royalist system, the hives have been painted in the post-revolutionary French flag colours of red, white and blue in a nod to the swarm of lawmakers below in the Fifth Republic's lower house.Six volunteer beekeepers from among the National Assembly staff will tend the hives, which are nestled together on a raised platform on the roof of a rear palace building.Despite their enviable Parisian vista, the bees will be packed tightly into their windowless homes, with each of the hives housing up to 50 000 bees in the summer months, a population that will drop to 15 000 in the winter.Left-wing lawmaker Laurence Dumont said estimated annual honey production should fill around 800 pots a year which would be given to schoolchildren on educational visits or charities.The farm ministry is working to revive beekeeping and reduce a dependence on imported honey, and Paris already sports bee hives atop other prestigious buildings including the Garnier Opera and the swanky Tour d'Argent left-bank restaurant.Meanwhile another species began doing its civic duty in the city this week as four fluffy black sheep were unleashed in a public garden under a new plan to use grazing animals, rather than machines, to trim city lawns.